The present invention relates to a drilling rig and associated method of use, including transportation, assembly, and operational benefits. Primary economic and safety concern related to land-based reserve development of oil and gas reserves is the expense of transporting and setting up drilling equipment at the well sites. Conventional drilling equipment for drilling oil and gas wells is heavy and bulky, making transportation of the equipment difficult. Many remote sites lack adequate road systems for transporting heavy equipment, increasing the amount of time that the drilling equipment needs for transportation between drilling sites.
Logistic issues associated with transporting drilling equipment not only increases the cost of transportation, but increases the capital cost of an energy exploration and development project. For instance, conventional drilling equipment is an expensive capital investment that remains unused during transportation. Further, the workers that operate the drilling equipment are generally not engaged in their primary job function during transportation times. Thus, extended periods of time used to transport drilling equipment can drastically increase the overhead associated with a given well operation. This translates into thousands of dollars for an energy company that is attempting to develop energy reserves.
Moving extremely heavy loads has generally been a complicated task because of the large forces involved in lifting and transporting the heavy loads. When possible, large loads are often transported by disassembling or breaking up the load into multiple smaller loads. However, this break-down and subsequent reassembly process can be very time consuming, especially when a heavy load is only to be moved a small distance, or needs to be repositioned.
For heavy loads that need periodic movement or adjustment, devices commonly referred to as “walking systems” were developed. Walking systems typically have multiple “pods,” “feet,” or “stompers.” These machines typically move the heavy loads over small distances in incremental stages without disassembly of the drilling systems. Walking systems are particularly useful for moving drilling systems where multiple wells are relatively closely spaced on a single pad thus allowing multiple wells to be drilled without rigging down or disassembling the rig.
Instead of using wheels driven by rotational forces to move heavy loads, walking machines typically use hydraulic lift cylinders to lift the load above a supporting surface, and then move or rotate the load relative to the supporting surface by pushing or pulling the load with hydraulic cylinders in combination with rollers or tracks in the walking machines. U.S. Pat. No. 5,921,336, issued Jul. 13, 1999, to Reed, discloses and teaches a walking structure device having a drilling rig substructure. U.S. Pat. No. 6,581,525, issued Jun. 24, 2003, issued to Smith, shows elongated beams under several rollers and lift cylinders, which allows the load from the lift cylinders and rollers to be spread over a large area.
Another important consideration to drilling operations is the safety of the personnel performing the operations. Drilling has inherent risks and hazards, and these are increased by transportation of the drilling equipment over significant distances. Safety considerations can shut down drilling operations if, for instance, essential drilling equipment becomes impaired or inoperable, or is just plain missing. When the drilling equipment is transported over extensive distances, essential equipment can easily be forgotten or misplaced. Further, safety is of extreme importance at remote sites, which typically are located large distances from medical assistance.
Accordingly, in the drilling industry, it is desirable to have a substructure and mast of a drilling system that: (a) moves quickly (i.e., breaks down into as few components as possible and transports easily with respect to individual package sizes/dimension (height, width, length, weight, etc.); (b) assembles quickly; (c) has a rig floor height to accommodate the various blowout preventers (BOPS) and rotating head assembly heights (nominally around 25 feet for maximum flexibility); (d) accommodates multiple well pads (including adapted for walking); and (e) disassembles quickly.
Design styles for drilling systems with substructures directed to achieve these desired attributes include (a) box-on-box substructures (such as disclosed in U.S. Pat. No. 6,161,358, issued Dec. 19, 2000, to Mochizuki et al.); (b) self-elevating telescoping box-on-box substructure (such as the National Oilwell Varco (Houston, Tex.) Box-In-Box substructure) or the Unit Drilling (Oklahoma City, Okla.) BOSS Rig substructure); (c) self-elevating parallelogram swing up winch or cylinder raised substructure with cantilevered drawworks raised mast (such as the National Oilwell Varco DRECO Slingshot drilling rig substructure); (d) self-elevating telescoping columns substructure with telescoping cylinder raised mast (such as the National Oilwell Varco Cabot and IRI 1500 substructures); and (e) self-elevating parallelogram swing up cylinder raised substructure with cantilevered cylinder raised mast (such as the Helmerich & Payne (Tulsa, Okla.) FlexRig3 drilling rig).
U.S. Pat. No. 4,569,168, issued Feb. 11, 1986, to McGovney et al., discloses and teaches a substructure for an oil derrick that includes a base frame, a top frame, and an intermediate bifurcated support frame (a pair of horizontally extending traveling frames). A linkage network of swingable leg members intercouples the base and traveling and top frames for movement in parallelism between collapsed and elevated conditions of the substructure. In the collapsed mode, the frame members are positioned in an adjacent relationship for presenting a low profile to a flatbed truck that allows a portable oil rig to be easily shifted onto the top frame and into alignment with the oil wellhead below. A block and tackle assembly operably engages the traveling frames and is coupled to the derrick hook carried by the traveling block of the oil derrick. Upon operation of the latter, the swingably mounted traveling frames move towards each other causing an elevation of the top frame so as to present a working space between the elevated oil derrick and oil wellhead. The traveling frames are locked one to the other to maintain the top frame at its elevated position with collapsible end sway braces precluding lateral shifting of the top frame and oil rig thereon. To relocate the rig at another site, the traveling frames are unlocked, which causes a load induced, downward movement of the swingable leg members and associated frames toward their collapsed position with a hydraulic buffer assembly regulating the speed of movement of the traveling frames (and thus the collapsing speed of the entire substructure).
There remains a need for a well-drilling system and method that is easy and less expensive to assemble and disassemble for transportation between land-based drilling sites.
There also remains the need for a well-drilling system and method that supports multi-well development pads. There also remains a need for a well-drilling system and method that is adapted for moving using a walking system without disassembly.
There also remains a need for a well-drilling system and method that provides increased safety for drilling operations.